[HWYSTR455]

5th time being pulled up, assuming they were sized (or checked) on the original build, and sized this upcoming time. But in my opinion, the bolts would still be good to use.

If you're leery about it, replace the bolts, and get the upgraded ones. Now would be the time to do that if you're having the rods sized.

I agree, top bearing half looks beaten from det. It's possible it's from being out of round, if the rods weren't originally sized/checked, but personally, I would replace the bolts, have them sized, and the crank checked too.

If you are going internally balanced, don't forget you need a neutral balancer, and would recommend an SFI one (if you don't already have one).


.

[Skip Fix]

If they are SPS good luck finding them! I needed their 7/16 nuts for some Crower billet rods. Crower had a close bolt in stock but no nuts. Had to turn down the shoulder on some ARPs. And no dimples for stretch on the bolts.
SPS has gone almost entirely aero fasteners

[Dragncar]

Originally Posted by PunchT37

I have some 4340 I beams from Ace. Full float.

I have a set of 6.8s.
Story on those rods right from the horses mouth. One day at RPM a guy came in with a set of Crower Billet rods and asked the head guy at RPM if they could copy them. They did just that.
I wish the cap was a little beefier though. Someday I will put them to use on a milder engine. I have Molnar rods and a real set of Crower billets for heavier duty stuff.
If anyone knows where I can find a couple of Crower mid weightish BBC 6.8s let me know.

[steve25]

Please note that I am not saying that those rods have SPS bolts , I was just a torque example from there overall spec sheet that has 8 or so of the different rod bolts they made listed on it.

The required torque spec not only changes with bolt diameter, but with bolt length also.

[Formulas]

If you expand the photo you can see ARP 8740 .. You cant read it plainly but pay attention to the shine and shadows from the flash its not ARP 2000 or anything SPS

[hurryinhoosier62]

Originally Posted by scott70

These are probably the 5140 then. I do remember 2 different numbers, those are probably it. Replace the current arp bolts?

Absolutely. You have no idea IF they were installed and torqued correctly. I view new rod bolts as cheap insurance.

[hurryinhoosier62]

Originally Posted by PunchT37

I have some 4340 I beams from Ace. Full float.

Nearly all the 4340 rods I have seen that were sold by Ace were “H” beams, but I do recall RPM International ( Ace’s source) did sell an “ultra light” 4340 “I” beam rod.

[PunchT37]

Originally Posted by hurryinhoosier62

Nearly all the 4340 rods I have seen that were sold by Ace were “H” beams, but I do recall RPM International ( Ace’s source) did sell an “ultra light” 4340 “I” beam rod.

Mine were a 740`ish gram I beam. They sold a 720`ish "A" beam shortly after.

[scott70]

Originally Posted by HWYSTR455

5th time being pulled up, assuming they were sized (or checked) on the original build, and sized this upcoming time. But in my opinion, the bolts would still be good to use.

If you're leery about it, replace the bolts, and get the upgraded ones. Now would be the time to do that if you're having the rods sized.

I agree, top bearing half looks beaten from det. It's possible it's from being out of round, if the rods weren't originally sized/checked, but personally, I would replace the bolts, have them sized, and the crank checked too.

If you are going internally balanced, don't forget you need a neutral balancer, and would recommend an SFI one (if you don't already have one).


.

I use a pb1056ss. Internal balance it says. I put it on about 3-4 years ago, replacing the original balancer. The engine was originally balanced with the OEM balancer. When I put this on, I really wasn’t thinking of the balance, but it didn’t seem to affect it all.. sounds like a good idea if I get into this motor, which I probably will is to upgrade and replace the rod bolts. I find it odd that I don’t see any markings on these connecting rods at all saying a part number or a company. Or something.

[HWYSTR455]

If you get stuck with a rod bolt issue, and want to stay press-fit, the Eagles are fairly inexpensive, think they are in the $375-$400 range.

After going thru the rods you have, you may be close to that anyway.

Obviously, if you go floating, pretty sure you would need new pistons, and then the project-creep sets in.

The 4.25 balanced stroker kits are the least expensive out there, and if you add all your cleanup/rebuild costs up, you may be close to one of those anyway. The Butler ones are around $2400, think others vendors may be less, but that's a pretty good deal.



.

[hurryinhoosier62]

Originally Posted by Skip Fix

If they are SPS good luck finding them! I needed their 7/16 nuts for some Crower billet rods. Crower had a close bolt in stock but no nuts. Had to turn down the shoulder on some ARPs. And no dimples for stretch on the bolts.
SPS has gone almost entirely aero fasteners

SPS rod bolts haven’t been a “thing” in automotive applications in twenty-five years(?). All of our rod bolts in Continentals and Lycomings were manufactured by SPS. If you know the total length and grip length of the bolt as well as the diameter and thread pitch there is probably an SPS aircraft rod bolts that would work, but WHY would you want to pay more for ONE bolt than an entire set of ARP rod bolts cost?

[Skip Fix]

My Crower billets I bought used had the 12 point nuts tweaked a little when previous owner removed them. Buying new correct nuts would have been ideal as the shoulder on the ARP 7/16 nuts was 0.040 to big to fit in the rod recess. Had to have some turned down to still use decent rods.

[HWYSTR455]

Think I still have Crower nuts for the billet rods, and think they may still be available thru Crower, but haven't checked in a long time.

I would have to check, but those rods might still be in my 461. They are the 6.80 rods though.


.

[Skip Fix]

Nope Crower tech said only bolts. Turned down ARPs nuts seem to be OK had the rods resized to be sure they were OK.

[HWYSTR455]

Well, if you need some, email me at home, will dig for them. Think I have some bolts too. Doubt I have a full set, but will check.



..

[HWYSTR455]

Found this too, lists part numbers and torque specs. Also found a pic of the rods w new bolts, the rods are still in my 461 (now 463).


.

[scott70]

Took my engine over to the machine shop today with my list of things I wanted done and checked. Told him I wanted the connecting rod bolts replaced. Tonight I was thinking about if there is a certain amount of times you can heat up the small end for press fit pistons. Let’s say you’ve changed pistons a few times and they’re press fit. Does it make the small end weaker if it’s been done a couple of times? He’s rebalancing it to make it internal balance. He’s probably got to remove the pistons from the rods to do the balance?

[steve25]

When the bolts are replaced the rods then need to checked for roundness.

If there out then they get resized and that can be done with the piston on the rod .

The weight difference if any between your old bolts and new ones would not make for a need to rebalance the motor .

If a rod(s) do get resized make sure there is no chamfer put at the parting line that’s over .005”.

More then this and the much needed bearing crush will be reduced and with that up goes the probability of a spun bearing.

[scott70]

The engine is going to be switched to internal balance. We talked about the big end will have to be checked after the new rod bolts replaced. I’m wondering just how many times can the small end be heated up for pistons on and off or it doesn’t matter,,, it doesn’t affect the strength?

[Half-Inch Stud]

My Guess as a guide: Heated to 500F a few 1,000 times, with no fatigue. Above 500F thru 1300 F and the heat-treat set has a slippery slope.

Cherry orange after that and the grain reorientates, the heat anneals. At such orange level, I don't know about the proper cool-down or quench to restore strength. Probably an natural oil dip.

Cast or Steel?